Category Archives: Renewables and Energy

Online calculator helps to determine the costs and benefits of rooftop solar

Posted on August 21, 2017 | Leave a comment

Homeowners in San Diego County have a new tool when considering the costs and benefits of installing rooftop solar panels.

The local nonprofit Center for Sustainable Energy launched a web page this week that allows residents to see how much they could save on their electrical bills based on a number of factors.

The web-based “Solar Savings Calculator” is intended to inform consumers who are considering whether to contract with a particular installation company, said Christina Machak, senior research analyst for the center.

“The value proposition for solar depends on lowering a homeowner’s monthly electricity bills,” she said. “The calculator gives a household-specific look at what homeowners can shave off their monthly utility bills in actual energy and dollar savings.”

The calculator uses location data to determine how much sunlight a particular home gets exposed to, as well as energy consumption patterns for residential customers of San Diego Gas & Electric. Users can download a detailed history of their electricity use from the utility and then upload it the center’s website.

The tool also uses updated information on the state’s net-energy-metering program, which determines how customers are compensated for the solar power they generate. In general, if ratepayers produce more electricity than they consume in a given year, they are paid a wholesale market price, which is less than the retail price, for that excess energy.

What do you get when you sign up for a 100% green electricity plan?

Posted on July 10, 2017 | Leave a comment

For the first time, residents and businesses up and down the state can buy electricity plans touted as “100 percent green” in their quest to fight climate change or simply be more environmentally friendly.

They can enroll in these programs through California’s three major investor-owned utilities — San Diego Gas & Electric, Southern California Edison and Pacific Gas & Electric — or through the growing number of cities and counties that offer alternative power programs called community choice aggregation, or CCA.

Does this mean all the electricity flowing into those customers’ homes and offices is created with renewable energy? No.

When residents pay a roughly $5 to $10 premium on top of the average monthly bill to get a 100 percent green plan, the provider buys a corresponding amount of renewable energy on their behalf. Almost all of that green power comes from existing inventory, which is mixed with electricity generated from fossil fuels, and the situation isn’t expected to undergo a transformation until far more people enroll in 100 percent plans. Whether that explosion in demand takes years or decades to realize remains to be seen.

“It doesn’t mean that when a customer signs up for 100 percent green, there’s a crew overnight wailing away and putting together another 6 kilowatts of solar somewhere. It’s an administrative process,” said Bill Powers of San Diego, an electrical engineering consultant and a consumer advocate.

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How to make windows work for energy efficiency

Posted on December 12, 2016 | Leave a comment

windows

“Glazing is the weak point in the thermal envelope if you’re using standard glass and a standard frame like aluminium.”

Wheeler says a good rule of thumb to follow is to have windows making up no more than 25 per cent of the total floor area of the house, and to place them carefully.

“Once you go beyond that 25 per cent there will be a heat exchange through that house that no amount of insulation in the walls and roof will compensate for,” he says. “You need to look at position, orientation, size and how the windows open. And if you’re going to glaze more than 25 per cent, upgrade your glass.”

Australian Window Association CEO Tracey Gramlick says up to 40 per cent of a home’s heating energy can be lost through windows and up to 87 per cent of its heat gained through them, so it’s well worth investing in energy-efficient windows.